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& \\
\multicolumn{1}{|l|}{\hspace{0.5cm}\LARGE\bf\sf Active}
& \multicolumn{1}{|c|}{\large\em An electronic publication dedicated to}\\ [0.3cm]
\multicolumn{1}{|l|}{\hspace{0.5cm}\LARGE\bf\sf Galaxies} & \multicolumn{1}{|c|}{\large\em the observation and theory of}\\ [0.3cm]
\multicolumn{1}{|l|}{\hspace{0.5cm}\LARGE\bf\sf Newsletter} & \multicolumn{1}{|c|}{\large\em active galaxies}\\ [0.3cm]
\hline
& \\
\multicolumn{1}{|c|}{\large\bf\sf No. 3 --- December 1996 } &
\multicolumn{1}{|c|}{\bf\sf Editor: Anthony Holloway (ajh@ast.man.ac.uk)} \\ [-0.1cm]
& \\ \hline
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\end{center}
\small
\vspace*{1cm}
\begin{center}
{\Large\sf From the Editor}
\end{center}
\vspace*{0.6cm}
This month we have another new addition to the newsletter, details of
conference proceedings. This conference has all the papers on-line to
read or download as postscript files. The newsletter mailing list is
increasing in size, now with 309 subscribers, but still with room for
more if you know someone who you think would like to receive it. The
deadline for the next issue will be 26th January.
Merry Christmas and a happy new year!
Ant.
\vspace*{1cm}
\begin{center}
{\Large\sf Conference Proceedings}
\end{center}
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Jet-cloud interactions in active galaxies}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{N.E. Clark, C.N. Tadhunter \& M. Villar-Martin}}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
{Department of Physics, University of Sheffield, Sheffield S3 7RH, UK} \\
%% Within the following brackets you place your text:
{A workshop on `Jet-cloud interactions in active galaxies' was held at the
University of Sheffield on 8th July 1996. The workshop was a resounding
success, with a number of fascinating talks and lively debate. Both theoretical
and observational aspects of jet-cloud interactions in radio galaxies and
seyfert galaxies were presented and discussed in the course of the workshop.}
% Here you write which journal accepted your paper, for example:
%% Here you may write the e-mail address of one or more of the authors
%% who will act as contact person for preprint requests and
%% details of availability of the paper via the World Wide Web. For example:
{The proceedings of this workshop are now available on-line, at
http://www.shef.ac.uk/$\sim$phys/research/astro/conf/}
% http://www.shef.ac.uk/~phys/research/astro/conf/
% if reading the latex source
\vspace*{1cm}
\begin{center}
{\Large\sf Abstracts of recently accepted papers}
\end{center}
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{A Study of Cores in a Complete Sample of Radio Sources}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{R. Morganti$^{1,2}$, T.A. Oosterloo$^{2}$, J.E. Reynolds$^2$, C.N.
Tadhunter$^3$\ and V. Migenes$^2$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Istituto di Radioastronomia, CNR, via Gobetti 101, I-40129 Bologna,
Italy}\\
$^2$ {Australia Telescope National Facility, CSIRO, P.O. Box 76, Epping, NSW
2121, Australia}\\
$^3$ {Department of Physics, University of Sheffield, Sheffield S3, UK}
%% Within the following brackets you place your text:
{
The high resolution provided by the Parkes-Tidbinbilla real-time
interferometer (PTI) has been used to measure the core flux density for a
complete sample of radio sources. Lower resolution maps are already available
for most of these objects together with optical (spectroscopic) data. The new
data show that an inverted spectral index $(\alpha \sim -0.3, S \propto
\nu^{-\alpha})$ could be characteristic of {\sl all} the nuclei, going from
low-luminosity radio galaxies to powerful quasars. Taking this spectral index
into account, the measured flux density does not change very much, going from
a scale of tens of kpc (corresponding to the low-resolution observations) to
the (sub)kpc scale of the new observations. Thus, most of the flux observed
in the central region originates in a sub-kpc area.
With the new PTI data we obtain a better estimate of the radio core dominance
($R$), i.e. the ratio between the core and the extended radio flux. This
parameter is claimed to be a good indicator of the orientation of the beamed
radiation with respect to the line of sight and hence a very important
parameter for testing `unified schemes' for active galactic nuclei (AGN).
Using this parameter, together with optical spectroscopic information, we find
that the radio core dominance shows different distributions for different
radio and optical characteristics. A statistically significant difference in
the distribution of $R$ is observed between FR I and FR II radio galaxies,
supporting the idea that low-power sources are less affected by beaming
because they have, on average, a lower Lorentz factor. Among the FR II radio
galaxies, NLRGs (narrow-line radio galaxies) show the lower value of $R$ while
the BLRGs (broad-line radio galaxies) have the largest $R$. Moreover, the
median value of $R$ for BLRGs is lower than for steep-spectrum quasars (SSQ)
even after a number of selection effects are taken into account. This result
can be explained in the framework of unified schemes for AGN assuming that in
the BLRGs we are seeing more directly into the nucleus, although not as much
as in SSQs.
}
% Here you write which journal accepted your paper, for example:
{ Accepted by MNRAS }
%% Here you may write the e-mail address of one or more of the authors
%% who will act as contact person for preprint requests and
%% details of availability of the paper via the World Wide Web. For example:
{E-mail contact: rmorgant@atnf.csiro.au, preprint available at
http://www.atnf.csiro.au/$\sim$toosterl/2jy/pti-html/pti-html.html (html)
and ftp://ftp.atnf.csiro.au/pub/people/toosterl/www/pti-paper.ps.gz (gzipped
postscript)}
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{ Radio, optical and X-ray observations of PKS2250-41:
a jet/galaxy collision?}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ N.E. Clark$^{1}$, C.N. Tadhunter$^{1}$,
R. Morganti$^{2,3}$, N.E.B. Killeen$^{3}$, R.A.E. Fosbury$^{4}$,
R.N. Hook$^{4}$, W. Siebert$^{5}$, and M. Shaw$^{1}$}}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^{1}$ {Department of Physics, University of
Sheffield, Sheffield S3 7RH, United Kingdom}\\
$^{2}$ {Instituto di Radioastronomia, C.N.R., via Gobetti 101, Bologna,
Italy}\\
$^{3}$ {ATNF, CSIRO, PO Box 76, Epping NSW 2121, Australia}\\
$^{4}$ {ST-ECF/ESO, Karl-Schwarzschild Strasse 2, D-85740 Garching bei Munchen,
Germany.}\\
$^{5}$ {Max-Planck Institut f\"{u}r Extraterrestrische Physik,
Gressenbachstra$\ss$e, D-85740 Garching, Germany.}
%% Within the following brackets you place your text:
{ New optical, radio and X-ray observations are used to investigate the
morphology, ionization and kinematics of extended structures in the host
galaxy of the radio source PKS2250-41 ($z=0.308$). The data provide
compelling evidence for a powerful interaction between the radio jets and the
ambient interstellar medium. Not only do [OIII] emission-line images show
spectacular extended arc structures associated with the radio lobes on both
sides of the galaxy nucleus on a scale of 40 -- 65 kpc (H$_{0}=50$ km
s$^{-1}$ Mpc$^{-1}$, q$_{0}=0.0$ used throughout, giving an angular scale of
6.0 kpc arcsec$^{-1}$), but there is also large depolarization in the western
radio lobe at the position of the western emission-line arc. Optical
long-slit spectra of the extended emission-line regions provide the first
convincing evidence that the radio jets have a role in ionizing the warm gas
in powerful radio galaxies: while the low ionization [NII] and [SII] lines are
broad (FWHM $ \sim 300-500$ km s$^{-1}$) across the entire emission-line
nebulosity, the higher ionization [OIII] lines are much narrower in the
western emission-line arc (FWHM $= 240 \pm 10$ km s$^{-1}$). This
anti-correlation between linewidth and ionization is difficult to explain in
terms of central source photoionization, but is entirely consistent with
ionization by fast shocks driven by the radio jets. Further evidence for
shocks is provided by the minimum in the ionization state at the position of
the radio lobes, and by [OIII]4363/(5007+4959) and HeII/H$\beta$ diagnostic
ratios which are more consistent with shocks than with photoionization. The
spectacular nature of the jet/cloud interaction in this object is best
explained in terms of a direct collision between the radio jet and a companion
galaxy in the surrounding group. This model is supported by the detection of
a blue continuum source in the western arc with a colour and luminosity
characteristic of late-type spiral galaxies.
}
% Here you write which journal accepted your paper, for example:
{ Accepted by MNRAS }
%% Here you may write the e-mail address of one or more of the authors
%% who will act as contact person for preprint requests and
%% details of availability of the paper via the World Wide Web. For example:
{E-mail contact: n.e.clark@sheffield.ac.uk, preprint available as HTML\\
(http://wwwatnf.atnf.csiro.au/Preprints/1996oct/1996oct0002/1996oct0002.html)
and gzipped postscript\\
(ftp://ftp.atnf.csiro.au/pub/preprints/1996oct/1996oct0002.ps.gz)
}
\vspace*{0.6cm}
{\large\bf{Coronal lines in active galactic nuclei}}
{\bf{E. Oliva$^1$ }}
$^1$ {Osservatorio Atsrofisico di Arcetri, largo E. Fermi 5, I-50125,
Firenze, italy}
{
Recent observations show that the coronal line region (CLR)
is small (a few $\times$10 pc),
has large column densities ($N\approx10^{22}$ cm$^{-2}$),
lies close to and is probably photoionized by the AGN.
Coronal lines give information on Ne, Mg, Si, S, Ca, Fe, abundances,
on the dust content and on the dynamics of the CLR, and
can be used to trace hidden AGN.
If photoionized, coronal lines could be used to reconstruct
the AGN spectrum at 100-400 eV.
However, a proper understanding of the results require a
careful use of photoionization codes, since the ionization parameter
at the inner face is probably meaningless for CLR models,
and a settlement of the `highly variable' atomic parameters
for coronal lines.
A shock model for the CLR in NGC1068 needs collisional ionization of
$\ge$600 $M_\odot$/yr of dense ($n>10^4$ cm$^{-3}$) gas
within $10^{10}$ $M_{\odot}$
which must be continuously supplied to the CLR.
}
{To appear in {\it IAU Colloq. 159, Emission Lines in Active
Galaxies: New Methods and Techniques}, ed. B.~M. Peterson, F.-Z. Cheng, \&
A.~S. Wilson (San Francisco: ASP).}
{E-mail contact: oliva@arcetri.astro.it, preprint available at
http://www.arcetri.astro.it/$\sim$oliva}
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Jet Cocoons and the Formation of Narrow Line Clouds in Seyfert Galaxies}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ W. Steffen$^{1}$, J.L. G\'omez$^{1,2}$, R.J.R. Williams$^{1,4}$, A.C. Raga$^{3}$ and A. Pedlar$^{5}$
}}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^{1}${Department of Physics and Astronomy, University of Manchester, Schuster Laboratory, Oxford Road, Manchester M13 9PL, UK} \\
$^{2}${Instituto de Astrof\'{\i}sica de Andaluc\'{\i}a, CSIC, Apdo. 3004, Granada 18080, Spain} \\
$^{3}${Instituto de Astronom\'{\i}a, UNAM, Apdo. Postal 70-264, 04510 Mexico, D.F., Mexico} \\
$^{4}${Dept. of Physics and Astronomy, The University, Leeds LS2 9JT, UK} \\
$^{5}${Nuffield Radio Astronomy Laboratories, University of Manchester, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK} \\
%% Within the following brackets you place your text:
{We present non-adiabatic hydrodynamic simulations of a supersonic
light jet propagating into a fully ionized medium of uniform density
on a scale representative of the narrow line region (NLR) in
Seyfert galaxies with associated radio jets. In this regime the
cooling distance of the swept up gas in the bowshock of the jet is of
the same order as the transverse extent of the jet bowshock, as
opposed to the more extreme regimes found for more powerful
adiabatic large scale jets or the slow galactic jets which have been
simulated previously. We calculate the emissivity for the H$\alpha$ line
and radio synchrotron emission. We find that the structure of the line
emitting cold envelope of the jet cocoon is strongly dependent on the
non-stationary dynamics of the jet head as it propagates through the
ambient medium.
We observe the formation of cloud-like high density
regions which we associate with NLR clouds and filaments. We find
that some of these clouds might be partially neutral and represent
sites of jet induced star formation. The calculated H$\alpha$ flux and the
spectral line width are consistent with NLR observations. The
simulation of the radio-optical emission with radiative cooling
confirms the basic result of the geometric bowshock model developed
by Taylor et al (1989) that the start of noticeable optical line
emission can be significantly offset from the hotspot of the radio
emission. However, the time-dependent nature of the jet dynamics
implies significant differences from their geometric bowshock model.
}
% Here you write which journal accepted your paper, for example:
{ Accepted by Monthly Notices of the Royal Astronomical Society, MNRAS }
%% Here you may write the e-mail address of one or more of the authors
%% who will act as contact person for preprint requests and
%% details of availability of the paper via the World Wide Web. For example:
{E-mail contact: wsteffen@ast.man.ac.uk, preprint available at http://axp2.ast.man.ac.uk:8000/Preprints.html}
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{A ROSAT observation of the warm-absorbed soft X-ray
spectrum of NGC 4051}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ Stefanie Komossa$^1$ \ and Henner Fink$^1$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Max-Planck-Institut f\"ur extraterrestrische Physik, 85740 Garching, Germany} \\
%% Within the following brackets you place your text:
{ We present and analyze a pointed ROSAT PSPC observation of the
Seyfert galaxy NGC 4051. The X-ray spectrum consists of a powerlaw
modified by absorption edges and an additional soft excess during
the high-state in source flux. Modeling the spectrum in terms of
warm absorption yields a large column density of the ionized
material of $\log N_{\rm w}$ = 22.7 and an ionization parameter of
$\log U$ = 0.4. These properties are essentially constant
throughout the observation, whereas the luminosity changes by more
than a factor of 4. The underlying powerlaw is in its steepest
observed state, with a photon index $\Gamma_{\rm{x}}$ = --2.3.
Consulting information from optical observations, evidence for a
separate EUV bump component in NGC 4051 is provided. The impact of
several parameters on the deduced properties of the ionized material
is critically assessed. In particular, the influence of dust mixed
with the warm gas is explored and shown to constrain the history or
density of the absorber. The absorber-intrinsic optical-UV emission
(and absorption) line spectrum is predicted and the possibility of a
warm absorber origin of one of the observed emission line regions in
NGC 4051 is investigated. Consequences for the narrow-line Seyfert
1 character of NGC 4051 are discussed. }
% Here you write which journal accepted your paper, for example:
{ Accepted by Astronomy \& Astrophysics }
%% Here you may write the e-mail address of one or more of the authors
%% who will act as contact person for preprint requests and
%% details of availability of the paper via the World Wide Web. For example:
{E-mail contact: skomossa@rosat.mpe-garching.mpg.de, preprint
available at astro-ph@babbage.sissa.it, astro-ph/9612038}
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Origin of the viewing-angle dependence of
the optical continuum emission in quasars}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ Joanne C. Baker$^{1,2}$ }}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {MRAO, Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE, UK} \\
$^2$ {Dept. of Astrophysics and RCfTA, University of Sydney, NSW 2006,
Australia} \\
%% Within the following brackets you place your text:
{
The orientation-dependence of the optical continuum emission in
radio-loud quasars is investigated using a new, complete sample of
low-frequency-selected quasars, the Molonglo Quasar Sample (MQS).
The optical continuum is found to be highly
anisotropic, brightening continuously from lobe- to
core-dominated quasars by 3--5~mag.
It is argued that aspect-dependent extinction,
rather than relativistic boosting as has been previously proposed,
provides the simplest explanation consistent with the data.
The reddening hypothesis is supported by both the steeper optical
slopes and the larger Balmer decrements found in lobe-dominated
quasars, as well as the stronger anisotropy seen at blue wavelengths.
The dust responsible is shown to be physically associated with the
quasar, lying mostly at radii between the broad and narrow-line regions
in a clumpy distribution. Such a geometry is reminiscent of a torus.
However, substantial numbers of dust clouds must lie within the
torus opening angle, contributing to an increasing average optical
depth with increasing viewing angle away from the jet axis, $\theta$.
In addition, the ratio of [O\,{\sc iii}]\,$\lambda \lambda$4959,5007 to
[O\,{\sc ii}]\,$\lambda 3727$ line flux is shown to be aspect dependent,
and is consistent with partial obscuration of [O\,{\sc iii}] at large $\theta$.
Trends of broad-line equivalent widths with $R$ are also presented,
including evidence for the luminosity dependence of
$W_{\lambda}$\,(Mg\,{\sc ii}\,$\lambda$2798). }
% Here you write which journal accepted your paper, for example:
{ Accepted by MNRAS }
%% Here you may write the e-mail address of one or more of the authors
%% who will act as contact person for preprint requests and
%% details of availability of the paper via the World Wide Web. For example:
{E-mail contact: jcb@mrao.cam.ac.uk,
preprint available at
http://xxx.soton.ac.uk/abs/astro-ph/9611202 }
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Differences in emission line spectrum in maximum and minimum
of the nucleus brightness of Seyfert galaxy NGC 7469}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{I.I. Pronik, L.P. Metik, N.I. Merkulova}}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Crimean Astrophysical Observatory, Nauchny, Crimea, 334413, Ukraine} \\
%% Within the following brackets you place your text:
{
We have compiled the data on relative intensities, fluxes and profiles
of emission lines of the NGC 7469 nucleus spectrum observed in the optical
region by many authors during 1966 -- 1986. The aim of our investigation
is to reveal differences in the characteristics of the emission lines
in maxima and minima of the nucleus brightness. The distinction was
revealed for relative intensities, fluxes and profiles. During the
extreme maxima profiles of H$_\gamma$, H$_\beta$ and H$_\alpha$ lines,
colour indices of the nucleus and its high level of accretion rate
are resemble those of QSOs. On the other hand, during the deep minimum
1989 the nucleus had the properties of Sy2 type. There is a relation
between variable fluxes of H$_\beta$ and [OIII] $\lambda$ 5007\AA\ lines
which is different for minima and maxima of the nucleus brightness.
The fluxes of the [OIII] $\lambda$ 5007\AA\ line during the minima of
the nucleus brightness are systematically higher than those in
maxima. Above mentioned peculiarities of the emission lines
in the NGC 7469 nucleus can be understood in terms of increasing
of electron temperature, electron density and velocities of the nucleus
gas from minima to maxima.}
% Here you write which journal accepted your paper, for example:
{Accepted by Astrphys.Space Sci}
%% Here you may write the e-mail address of one or more of the authors
%% who will act as contact person for preprint requests and
%% details of availability of the paper via the World Wide Web. For example:
{E-mail contact: ipronik@crao.crimea.ua}
\vspace*{1cm}
\begin{center}
{\Large\sf Thesis Abstracts}
\end{center}
\vspace*{0.6cm}
%% Between these brackets you write the title of your paper:
{\large\bf{Jet-cloud interactions in powerful radio galaxies}}
%% Here comes the author(s) of the paper, please indicate within $^...$
%% the number which corresponds to the institute of each author.
{\bf{ Neil Clark$^1$}}
%% Here you write your institute name(s) and address(es),
%% the number in $^..$ indicates your author number, for example:
$^1$ {Department of Physics, University of Sheffield, Sheffield S3 7RH, UK} \\
%% Within the following brackets you place your text:
{Extended emission line regions are observed in a large fraction of powerful
radio galaxies, and are found to be preferentially aligned along the axes of
the extended radio emission. The two main models which have been proposed to
explain this alignment effect are: a) illumination of ambient gas
by an anisotropic central continuum source; and b) jet-cloud interactions. The
relative effect of these two competing physical processes on the properties of
the extended line-emitting gas is currently uncertain.
This thesis is based on a detailed optical spectroscopic
study of four powerful radio galaxies: PKS~2250$-$41 ($z=0.308$), 3C~171
($z=0.238$), 4C~29.30 ($z=0.0647$) and Coma~A ($z=0.0858$). The effects of jet-cloud interactions upon the morphology, physical conditions, kinematics and
ionization of the extended line-emitting gas in these four sources is
investigated. From this study it is clear that jet-induced shocks can have a
dramatic effect on the line-emitting gas over a range of spatial scales and
radio powers. The evidence for jet-induced shocks includes: close
radio-optical associations; high pressures in the extended gas; low
ionization states and ionization minima associated with the radio hot spots;
line-splitting, and large line widths and velocity gradients; an
anti-correlation between line width and ionization state; and high [OIII]
temperatures and low HeII/H$\beta$ ratios consistent with shock ionization.
Pronounced UV continuum excesses are also observed associated with the
extended line emission in all four sources, and it is found that a large
proportion of this UV excess is due to nebular continuum emission from the
shocked clouds.
Although the sample studied here is small, there are many similarities
between these four sources and the powerful radio galaxies observed at high
redshifts. This implies that jet-induced shocks are also important in high
redshift radio galaxies.}
% Here you write which journal accepted your paper, for example:
{PhD thesis, submitted June 1996}
%% Here you may write the e-mail address of one or more of the authors
%% who will act as contact person for preprint requests and
%% details of availability of the paper via the World Wide Web. For example:
{E-mail contact: n.e.clark@sheffield.ac.uk}
\vspace*{1cm}
\begin{center}
{\Large\sf Jobs}
\end{center}
\vspace*{0.6cm}
\vspace*{1cm}
\begin{center}
{\Large\sf Meetings}
\end{center}
\vspace*{0.6cm}
\begin{center}
\fboxrule0.02cm
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\fbox{\rule[-0.9cm]{0.0cm}{1.8cm}{\parbox{14cm}
{
The Active Galaxies Newsletter is available on the World Wide Web.
You can access it via the University of Manchester home page :-
http://axp2.ast.man.ac.uk:8000/$\sim$ajh/agn/
}}}
% http://axp2.ast.man.ac.uk:8000/~ajh/agn/
% if you are reading the latex source.
\end{center}
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